R in a Nutshell, 2nd Edition

Importing Data From Databases

It is very common for large companies, healthcare providers, and academic institutions to keep data in relational databases. This section explains how to move data from databases into R.

Export Then Import

One of the best approaches for working with data from a database is to export the data to a text file and then import the text file into R. In my experience dealing with very large data sets (1 GB or more), I’ve found that you can import data into R at a much faster rate from text files than you can from database connections.

For directions on how to import these files into R, see Text Files.

If you plan to extract a large amount of data once and then analyze the data, this is often the best approach. However, if you are using R to produce regular reports or to repeat an analysis many times, then it might be better to import data into R directly through a database connection.

Database Connection Packages

In order to connect directly to a database from R, you will need to install some optional packages. The packages you need depend on the database(s) to which you want to connect and the connection method you want to use.

There are two sets of database interfaces available in R:

• RODBC. The RODBC package allows R to fetch data from ODBC (Open DataBase Connectivity) connections. ODBC provides a standard interface for different programs to connect to databases.

• DBI. The DBI package allows R to connect to databases using native database drivers or JDBC drivers. ...